The present invention relates to an improved gas mask structure, and more particularly to a gas mask having shorter length and is equipped with a second filter body disposed in front of the filter body for filtering off larger particles such as dust and powder.
FIG. 5 shows a conventional gas mask used in spraying of agricultural chemicals. The gas mask includes a helmet (not shown) and a respiratory cup 81 for a user to wear on the nose and mouth. The respiratory cup 81 is connected with one end of a respiratory tube 82. The other end of the respiratory tube 82 is connected with a filter unit 8 having a filter body and a blower (not shown). The blower sucks in air and makes the air filter through the filter body and go through the respiratory tube 82 to the respiratory cup 81 for the user to breathe clean and cool air. However, in practical use, such gas mask still has some shortcomings as follows:
1. Inconvenience in use: The filter unit 8 is worn on the waist of the user and the air is conducted through the respiratory tube 82 to the respiratory cup 81. However, the distance from the waist to the nose and mouth is considerably long. Moreover, in order to permit the user""s head and body to more freely move, the respiratory tube 82 must be even longer. In a narrow space, the long respiratory tube 82 will obstruct the user from working. Especially, when spraying the agricultural chemicals, the user must carry a spraying equipment. Under such circumstance, the long respiratory tube 82 will lead to great inconvenience in use.
2. Great pressure loss of the respiratory tube: The respiratory tube 82 is in a winding state. This leads to pressure loss of the flowing air and results in low efficiency of the blower and waste of energy.
3. Heavy equipment: The conventional gas mask has numerous components including helmet, respiratory tube cup 81, respiratory tube 82 and filter unit 8 and is quite heavy. In addition, the long respiratory tube 82 must be co-used with a blower with greater power for sending air with sufficient pressure. Therefore, generally, the blower often cooperates with a chargeable battery (not shown). Such battery is very heavy and makes it more inconvenient to use the gas mask.
In order to eliminate the above shortcomings of the conventional gas mask, an improved gas mask as shown in FIGS. 6 and 7 has been developed. A motor 91 and a fan 92 are disposed in a front cup body 9 of the gas mask for directly sucking air. A filter body 93 serves to filter off the harmful materials entrained by the air and directly send the air to a rear cup 94 for a user to breathe. Accordingly, the power of the motor 91 will not be lost so that the working efficiency of the motor 91 and the fan 92 is increased. In addition, such gas mask can be directly worn on the face without intervening with the movement of other parts of a user""s body. However, in practical use of such gas mask in different working sites, for example, in the working site of a carpenter, wooden chips and powder are often produced, which tend to block the filter body 93 made of activated carbon. Under such circumstance, the filter body 93 will lose its normal function and must be frequently replaced with a new one. The activated carbon-made filter body 93 is manufactured at high cost so that a lot of money will be expensed.
Moreover, a check membrane 95 is horizontally disposed on the bottom of the rear cup 94 for conveniently breathing. The check membrane 95 has a considerable width which elongates the length of the rear cup 94. In addition, the cells 97 in the cell seat 96 are also horizontally positioned so that the entire length of the gas mask is increased. As a result, when wearing such gas mask, the filter body 93 is far spaced from the user""s face. This increases the torque and makes the user feel heavier to wear the gas mask. For shortening the length, the number of the cells 97 must be reduced. However, this will lead to insufficient power and make it necessary to frequently replace the cells 97.
It is therefore a primary object of the present invention to provide an improved gas mask structure having a second filter body disposed in front of the filter body. A cover body is screwed on a fixing seat of the front cup body to fix the filter body therein and tightly hold the second filter body. The second filter body serves to filter off larger particles such as dust and powder so as to prevent the filter body from being blocked thereby. Therefore, the using life of the filter body is prolonged and the cost is reduced.
It is a further object of the present invention to provide the above gas mask structure from which the second filter body can be removed for use in different working sites.
It is still a further object of the present invention to provide the above gas mask structure having shorter length so that the torque of the front end of the gas mask is reduced and a user can more comfortably wear the gas mask.
The present invention can be best understood through the following description and accompanying drawings wherein: